The present invention relates to a multiple staged rotary switch for use in various controllers as in automobiles.
When the driver of a car controls a variety of apparatuses (such as an audio apparatus and an air conditioner) of the car, he or she should be able to fumble for and operate switches thereof without changing his or her eyes from the front. If the switches were of push button type, the driver could not easily fumble for them. In addition, while the driver is fumbling for such a switch, he or she may sometimes press incorrect switches.
On the other hand, when a multiple staged rotary switch is used, the driver can easily fumble for and correctly control it. Moreover, when the multiple staged rotary switch is used, it can be prevented from incorrectly being operated. In other words, unless the driver rotates the switch, it is never operated. Thus, in the multiple staged rotary switch, the possibility of unintended operations can be reduced. Therefore, the multiple staged rotary switches are being increasingly used.
FIG. 1 shows the construction of a conventional multiple staged rotary switch. In this switch, rotary switches 1, 2, and 3 are multiply staged. The rotary switches 1, 2, and 3 have drive shafts 6, 5, and 4, respectively. The drive shafts 4, 5, and 6 are concentrically formed. The more inner the shafts are the more they extend in the axial direction thereof. Knobs 7, 8, and 9 are mounted on end portions of the drive shafts 4, 5, and 6, respectively. With the knobs 7, 8, and 9, the rotary switches 1, 2, and 3 are operated, respectively.
Electric contact signals of the rotary switches 1, 2, and 3 are extracted from wiring boards 11, 12, and 13, respectively. The wiring boards 11, 12, and 13 are electrically connected to a main wiring board 14. The main wiring board 14 and the rotary switches 1, 2, and 3 are accommodated in a case 15. A lead cable 16 connected to the main wiring board 14 is connected to apparatuses to be controlled. Thus, the case 15 can be disposed at any position in the automobile corresponding to the length of the lead cable 16. For example, the case 15 may be disposed at a position where the driver can reach it with his or her hand.
As shown in FIG. 1, since the conventional multiple staged rotary switch is constructed of the rotary switches 1, 2, and 3 which are staged, the thickness H of the case 15 becomes large. In this multiple staged rotary switch, when the driver turns the knob 7, 8, or 9 clockwise or counterclockwise and then releases it, it is automatically returned to its rotation reference position (home angle position) by the tension of a spring coil thereof. When a knob is turned clockwise or counterclockwise by a predetermined angle (for example, 20.degree.) from a predetermined rotation reference position, a contact signal is generated. Whenever the contact signal is generated, the state of the apparatus to be controlled is changed by one step in the plus or minus direction. For example, when the knob 9 is turned by the predetermined angle from the rotation reference position clockwise, one contact signal is generated. The contact signal causes the sound volume of for example an audio apparatus to be varied by one step in the plus direction. When this operation is repeated, the sound volume increases. In contrast, when the knob 9 is rotated by the predetermined angle counterclockwise, another contact signal is generated. This contact signal causes the sound volume of the audio apparatus to be varied by one step in the minus direction. When this operation is repeated, the sound volume decreases.
Since the rotary switches 1, 2, and 3 are provided with respective spring coils which produce tensions, the thickness T of the rotary switches 1, 2, 3 becomes comparatively large. This too, means that the thickness H of the case 15 must be large.